Security Tools
Entropy to Password Length Calculator
Enter a target entropy in bits and a character set to calculate the password length needed to reach it.
20 characters
to reach 128 bits of entropy
Uses length = ⌈target bits ÷ log₂(character set size)⌉. 128 bits is a commonly cited strong target; 80 bits is a more modest but still reasonable baseline for many use cases.
How to use this tool
- 1Enter your target entropy in bits.
- 2Choose a character set.
- 3See the required password length.
Frequently asked questions
How is this different from the password entropy calculator?+
That tool measures the entropy of a password you already have; this one works backwards, telling you how long a password needs to be to hit a target entropy.